William Henry wrote:
Hi all,
There is a requirement to be able to administratively move messages
from one queue to another and I'm looking for input regarding the/a
use case for this requirement.
It has been suggested that this is really a query/criteria based move
and it's really at a broker level. i.e. broker X please move all
messages from user johnz from queue A to queue B. Or broker X please
move all messages with topic Y from queue A to queue B. Queue B might
just be some sort of suspend queue while an administrator finds out
what johnz really wants or why messages of topic Y are not getting
consumed etc.
Has anyone any opinions or a concrete use case for this?
Regards,
William Henry
My two cents...
I think this is an administrative function that is performed on-demand
and has no lasting affect on the normal operation of the broker (i.e. no
filters or redirects are used). I also think that this feature will be
used primarily as a diagnostic tool.
Since messages are not modeled as management objects, this feature must
be coupled with a message-query feature. A management method (or set of
methods) can be implemented on queue objects to allow management users
to get information about the set of messages on a queue. For example:
- Get the top 10 most frequently seen reply-to fields and their
instance counts.
- Get the largest 10 message body sizes
- Get the top 10 most frequently seen [header-field] and instance counts.
- Get the number of messages with [header-field] matching a specified
value.
- Fill in a histogram of message sizes. The histogram buckets can be
supplied by the request or be fixed.
This query feature can be used to provide visibility into the content of
a blocked or slow-moving queue.
A companion feature can then be implemented that moves or copies all
messages meeting a certain criteria (i.e. size range or header field
match) to another queue. This allows the administrator to go to the
next level and actually view the full contents of messages (by
subscribing a consumer to the copied-to queue). It also allows the
administrator to remove messages from the queue to solve an application
problem.
Note that message query and message move/copy will probably require that
the queue be locked during the duration of the operation so these may be
expensive features. It would be good to find a way to implement these
on a flowing queue without locking.
-Ted
